html,
body {
    height: 100%;
}

body {
    background: url('../images/background2.jpg') center no-repeat;
    background-size: 100% 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}

.sign-box {
    display: flex;
    justify-content: center;
    width: 100%;
}

.input-group span {
    position: unset;
}

.form-signin {
    background-color: rgba(185, 216, 206, 0);
    top: -65px;
}

.input-Prompt {
    line-height: 47px;
}

#user-name,
#password,
#sign-buton {
    background-color: white;
    letter-spacing: 2px;
    font-family: Tahoma, Helvetica, Arial;
}

#sign-buton {
    letter-spacing: 20xpx;
    letter-spacing: 2px;
    font-family: Tahoma, Helvetica, Arial;
    background-color: rgba(190, 190, 190, 0.699);
    /*vertical-align：unset*/
}

#resiger-buton {
    letter-spacing: 20xpx;
    letter-spacing: 2px;
    font-family: Tahoma, Helvetica, Arial;
    background-color: rgba(190, 190, 190, 0.699);
    /*vertical-align：unset*/
}